Version 19 of Tcl syntax

Updated 2014-06-24 19:58:11 by AMG

Tcl's syntax is small enough to fit in the working memory of a typical human. -- Cameron Laird

Summary

The syntax of Tcl scripts is minimal and elegant. Additional layers of complexity and power are achieved via commands, which either recursively repeat some or all of the Tcl script evaluation process.

Description

A Tcl script conforms to the 12 rules of script construction, and is processed in the following way:

  1. Exactly one level of substitution and/or evaluation occurs in each pass through the Tcl interpreter, no more and no less.
  2. Each character is scanned exactly once in each pass through the interpreter.
  3. Any well-formed list is also a well-formed command; if evaluated, each element of the list will become exactly one word of the command with no further substitutions.
  4. Commands such as such as [[subst] and [[eval], submit their arguments to the Tcl interpreter, which scans them again.

See:

"args" == ARGH! Are they _really_ good for anything? , Brent Welch, comp.lang.tcl, 1994-02-01

See Also

#
{*}
specifies that each item in a list should be considered an individual argument to the current command
Dodekalogue
Hunt for Tcl Extensional Equivalents
Tcl Quoting
BNF for Tcl
double substitution
Brace your expr-essions
A parser's monolog
comment
Comments in expressions
Some suggestions, on how to do it.
An indentation syntax for Tcl
Why is Tcl syntax so weird
Syntax parsing in Tcl
Glossary for Tcl syntax
syntax
Static syntax analysis